The present invention is directed generally to silicon carbides and methods of making the same, and more particularly to a novel form of silicon carbide comprising ultra-microcrystallites of beta form and alpha form silicon carbide disposed on the surface of particles of a carbonaceous material. In making this novel product, the carbonaceous material is reacted with silica sand in a fluidized bed under specified conditions.
Some prior art methods of producing silicon carbide have been accomplished by means of the Acheson batch-type, charge resistor furnace. These methods have occasioned various disadvantages, including slowness of production and non-uniformity of product caused, inter alia, by the cyclic build-up and tear down necessary in this batch-type process.
Other methods of producing silicon carbide of small particle size have been proposed in the prior art. However, these methods have required very finely divided starting materials, and have necessitated a variety of combustible gases as reagents, such as methane and mixtures of hydrogen and oxygen, as well as other reagents, such as hydrofloric and sulfuric acid to produce the silicon carbide. Needless to say, the atmospheric pollution created by such processes has rendered them undesirable.
Other methods have been proposed in the prior art, which methods require the utilization of a vaporous halide of elements such as silicon, which has increased both costs and environmental pollutants.
Yet further methods of producing silicon carbide of small particle size have been proposed in the prior art. However, these methods have required very finely divided carbon and silica particles, which in turn require dispersion in a solvent, such as alcohol to obtain an intimate dispersion of the silica in carbon, which has further increased costs and the dangers of silicosis in workers.
Wherefore, in view of the deficiencies and defects of these prior techniques, improvement is required and the same is accomplished as set forth herein below in connection with the description of the novel methods and the products of the present invention.